Process of thermally treating and lubricating polyethylene terephthalate filaments and yarns



United States Patent" f 2,990,604 PROCESS OF THERMALLY TREATING AND LUBRI'CATING POLYETHYLENE TEREPH- THALATE FILAMENTS AND YARNS Kenneth Earnshaw MacConnack, Harrogate, England, assignor to Imperial Chemical Industries Limited, Millbank, London, England, a corporation of Great Britain No Drawing. Filed July 8, 1957, Ser. No. 670,383 Claims priority, application Great Britain July 18, 1956 5 Claims. (Cl. 28-72) This invention relates to an improved process for treating filaments and yarns which are heated in sliding contact With a hot metal surface and lubricating compositions for use in such processes.

In the manufacture of artificial filaments and yarns it is often necessary to heat the filaments or yarns whilst making sliding contact with a hot metal surface, e.g. during drawing, relaxing, crimping and heat setting. During subsequent textile operations such as winding, doubling, knitting and weaving the filaments and yarns are subjected to considerable friction whilst passing over various ceramic, metal and similar guides. To minimise friction and to facilitate these textile operations the filaments and yarns are provided with a lubricating composition during manufacture.

The known lubricating compositions comprise emulsions of a polymer or a mineral oil in Water, with suitable additives. These lubricating compositions although satisfactory for the subsequent textile operations at room temperature, give rise to a cumulative solid deposit when the filaments and yarns make sliding contact with hot metal surfaces, during prolonged running. Frequent cleaning of the hot metal surfaces becomes necessary, to prevent sticking and breakage of the moving filaments. Moreover wear of the hot metal surfaces takes place particularly during treatment of high tenacity filaments, such as polyethylene terephthalate filaments. Furthermore considerable care is necessary in compounding these lubricating compositions in order to obtain a relatively stable emulsion and to prevent separation during stoppages and during storage, when no agitation of the emulsion takes place.

According to my invention, in a process for treating filaments and yarns by heating in sliding contact with a hot metal surface in the presence of a lubricating composition, I provide the improvement which comprises using as lubricating composition an aqueous solution containing up to 20% by weight of a polyethylene oxide condensate and up to by weight of an antistatic agent. Preferably the solution also contains up to 1% by weight of a boundary lubricant.

The improvement of the treatment of my invention becomes most apparent when the filaments or yarn are making sliding contact with a metal surface heated above 140 C. particularly at low transverse pressures, e.g. when the filaments make tangential contact with a substantially flat metal surface such as a hot plate. There is no formation of solid deposits from my lubricating compositions under these conditions, which bring about a considerable amount of deposition from the lubricants'of the prior art. At high transverse pressures, e.g. when the filaments or yarn are drawn round a hot pin, which in the case of polyethylene terephthalate filaments is heated to above 80 C., wear of the metal is greatly reduced using the composition of my invention as opposed to those of the prior art.

The preferred polyethylene oxide condensates are the polyethylene glycols which are liquids at room temperature. From the polyethylene glycols those having an average molecular weight in the range 200-600 are particularly suitable. Solid polyethylene glycols of average molecular weight higher than '600 may be used if desired, but they must be soluble in the lubricating composition.

The antistatic agents, used in quantities of less than 10% by weight, must also be water soluble, and sufficiently volatile at the processing temperatures to prevent the formation of deposits during prolonged Any known agents may be used e.g. Lubrol W (registered trademark).

The inclusion of less than 1% of a material which acts as a boundary lubricant between the yarn and the hot metal surface, such as sodium stearate, assists smooth morning and reduces wear of the hot metal surface with which the filaments make contact. It is essential that the boundary lubricant should be soluble in the lubricating composition. When an antistatic agent is used this may be selected to assist the dissolving of the boundary lubricant. I have found the presence of Lubrol W (registered trademark) to assist the dissolving of sodium stearate. The slight tendency of some boundary lubricants e.g. fatty acid compounds, such as sodium steal-ate, to precipitate may be overcome by the inclusion of an alkali, such as sodium hydroxide, to raise the pH of the solution to between 8 and 9.

The prevention of the build up of solid deposits from the lubricating composition during prolonged running at high temperatures is assisted if the components do'not decompose on the hot metal surface. However, in some cases, e.g. in the special crimping process described in Speakman and MacLeod copending application, Serial No. 625,291, filed November 30, 1956, now Patent No. 2,974,391, it is necessary to use a metal surface at such high temperatures, i.e. above 270 C., that decomposition of the organic components of the lubricating composition cannot be prevented. 'The decomposition products in this case should be sufficiently volatile so that they do not form a cumulative solid deposit on the metal surface.

The lubricating compositions may be applied to the filaments at any stage of manufacture prior to making contact with the hot metal surface. Conveniently this may be done, e.g. in a melt spinning process after the filaments have solidified, as the filaments come from the spinneret. The amount of any particular lubricating composition picked up by the filaments using a given means for application will depend on their denier and the yarn structure. Suitable amounts are 5% to 20%. The lubricating composition may be applied by any means known in the art in such quantities that all the filaments are covered by the lubricating composition. When the major proportion of the water evaporates from the lubricating com.- position, the remaining components form an evenly distributed film on the filametn surface. It will be appreciated that small quantities of water are retained by any hygroscopic components of the lubricating composition. The amounts of the non-aqueous components of the lubricating composition remaining on the filaments should preferably be at least 0.2% on the weight of the filaments and the quantities of lubricating composition applied should therefore be adjusted accordingly.

The following examples, in which all parts and per= centages are by weight, illustrate but do not limit my invention.

thylene glycol of an average molecular erg t300 Parts Lubricant B A second composition is prepared consisting of:

Parts Polyethylene glycol 200 2 Antistatic agent Zelec NE (registered trademark) 3 Water 95 Lubricant C Another lubricating composition is prepared consisting of:

Parts Polyethylene glycol 200 2 Antistatic agent Heatex (registered trademark) 3 Water 95 Lubricant D Another lubricating composition is prepared from:

. Parts Polyethylene glycol 200 5 Antistatic agent Lubrol W 0.5 Sodium stearate-boundary lubricant 0.02 Water to make up 100 parts.

Lubricant E A lubricating composition similar to Example D is prepared using: Parts Polyethylene glycol 400 5 Antistatic agent Lubrol W 0.5 Sodium stearate-boundary lubricant 0.025 Water to make up 100 parts.

Lubricant F A similar lubricating composition to Example E is prepared using:

' Parts Polyethylene glycol 300 5 Antistatic agent Lubrol W 2 Sodium stearate-boundary lubricant 0.2

Water to make up 100 parts.

The lubricating compositions A to F are each applied to a separate large batch of solidified polyethylene terephthalate filaments as they come from the spinneret before being wound up as filament yarn, and prior to a drawing process. The amount of the non-aqueous components of the lubricating composition retained on the filaments is from 0.5% to 1% by wei'gth of the yarn. The batches of polyethylene terephthalate filament yarns are subjected to a drawing process, at speeds of at least 150 metres per minute during 14 days continuous drawing. Satisfactory drawing conditions at draw ratios up to 4.5 times are obtained using a hot pin at 85 C., followed by a hot plate at 175 C. Excellent filament yarns during 14 days continuous drawing are obtained and no build up of deposits and little wear on any of the hot chromium plated pins and plates is observed.

By comparison if the polyethylene terephthalate filaments are drawn under the same conditions as described but in the presence of an aqueous lubricating emulsion comprising a mineral oil, a Turkey red oil, triethanolamine and diethylene glycol, a brown cumulative'solid deposit is formed on the plates within 12 hours drawing, and the plates require cleaning after 48 hours drawing. If the deposits are not removed frequent filament breaks occur and the uniformity of the drawn filaments is impaired.

Other improvements were observed in this comparative trial and particularly the following were noted:

(a) A more even application of the lubricating compositions A to F is obtained than can be obtained with the lubricating emulsion of the comparison. The percentage coefficient of variation in the amount of finish applied is reduced to one third, compared with the lubrieating emulsion.

(b) No objectionable fuming occurs when the yarns are passed over the hot metal pins and plates, whereas the lubricating emulsion gives rise to considerable and objectionable fuming.

(0) With the lubricating composition F, for example, wear of the metal surfaces is considerably less, than with the lubricating emulsion.

EXAMPLE 2 A lubricating composition as described in Example 1 is used in a process for making potentially crimped continuous polyethylene terephthalate filaments by heating the moving continuous filaments while passing over a narrow heated metal surface so that the filaments are heated non-uniformly on one side only continuously along their length while under a tension to give a stretch to the filaments of not more than 10%, as described in the above-mentioned copending application Serial No. 625,291. The hot metal surface is heated to a temperature above 270 up to 900 C. Prolonged continuous running is obtained using the above lubricating composition and no build up on the hot metal surface occurs. Running speeds of at least 500 metres per minute are possible, when using the above lubricant, in quantities such that at least 0.3% of non-aqueous components of the lubricating composition is deposited on the filaments. The potentially crimped filaments are wound up and subjected to a heat relaxation treatment which develops the crimp.

By comparison if instead of the lubricating composition of Example 1 one of the known lubricating compositions is used, comprising an aqueous emulsion of a mineral oil, Turkey red oil, triethanolamine oleate and diethylene gly- C01 in water, a deposit is formed on the hot metal surface within 3 hours, which has to be removed. Operation has to be stopped and the hot metal surface allowed to cool before the deposit is removed. In spite of this cleaning, the number of filament breaks which cause laps, is increased 30 times and the number of complete breaks in the threadline, affecting all filaments simultaneously, is increased 20 times.

What I claim is:

1. A process for thermally treating and lubricating polyethylene terephthalate filaments and yarns when making sliding contact with stationary metal surfaces heated to above C., which comprises applying to said filaments an aqueous lubricating composition which is a solution and which consists essentially of 220% by weight of a polyethylene glycol having an average molecular weight between 200 and 600 and which by itself is a liquid at room temperature, and up to 10% by weight of an antistatic agent, so that the amount of the non-aqueous component of said solution on the filaments is at least 0.2% by weight of the filaments, and thereafter slidably contacting the filaments with said metal surface at a temperature above 140 C.

2. The process of claim 1, wherein said amount of said non-aqueous component on the filament is from about 0.5% to about 1% by weight of the filaments.

3. A process according to claim 1, wherein the aqueous solution also contains up to 1% by weight of a boundary lubricant.

4. A process according to claim 3, wherein sodium stearate is present in the aqueous solution 'as a boundary lubricant.

5. A process according to claim 3, wherein the aqueous solution contains a boundary lubrication and the pH of the solution is raised to between 8 and 9 by the inclusion of sodium hydroxide.

References Cited in the file of this patent UNITED STATES PATENTS 6 Wilkes et a1. Aug. 7, 1945 Myers Jan. 29, 1946 Sitzler et a1 Feb. 5, 1946 Rossin et a1 Aug. 10, 1954 Schofield Apr. 17, 1956 Kolb Aug. 14, 1956 Welles et a1 Oct. 8, 1957 Asten Dec. 23, 1958 Mooberry Jan. 12, 1960 Coplan et a1 Feb. 23, 1960 OTHER REFERENCES Tech. Review, vol. 55, No. 8, pages 425-427, June 1953, Electricity in the Textile Industry. Copy in 57-157AS- 

1. A PROCESS FOR THERMALLY TREATING AND LUBRICATING POLYETHYLENE TEREPHTHALATE FILAMENTS AND YARNS WHEN MAKING SLIDING CONTACT WITH STATIONARY METAL SURFACES HEATED TO ABOVE 140*C., WHICH COMPRISES APPLYING TO SAID FILAMENTS AN AQUEOUS LUBRICATING COMPOSITION WHICH IS A SOLUTION AND WHICH CONSISTS ESSENTIALLY OF 2-20% BY WEIGHT OF A POLYETHYLENE GLYCOL HAVING AN AVERAGE MOLECULAR WEIGHT BETWEEN 200 AND 600 AND WHICH BY ITSELF IS A LIQUID AT ROOM TEMPERATURE, AND UP TO 10% BY WEIGHT OF AN ANTISTATIC AGENT, SO THAT THE AMOUNT OF THE NON-AQUEOUS COMPONENT OF SAID SOLUTION ON THE FILAMENTS IS AT LEAST 0.2% BY WEIGHT OF THE FILAMENTS, AND THEREAFTER SLIDABLY CONTACTING THE FILAMENTS WITH SAID METAL SURFACE AT A TEMPERATURE ABOVE 140*C. 